6.4.6 The break Statement

The break statement jumps out of the innermost for, while, or do loop that encloses it. The following example finds the smallest divisor of any integer, and also identifies prime numbers:

     # find smallest divisor of num
     {
        num = $1
        for (div = 2; div*div <= num; div++)
          if (num % div == 0)
            break
        if (num % div == 0)
          printf "Smallest divisor of %d is %d\n", num, div
        else
          printf "%d is prime\n", num
     }

When the remainder is zero in the first if statement, awk immediately breaks out of the containing for loop. This means that awk proceeds immediately to the statement following the loop and continues processing. (This is very different from the exit statement, which stops the entire awk program. See Exit Statement.)

Th following program illustrates how the condition of a for or while statement could be replaced with a break inside an if:

     # find smallest divisor of num
     {
       num = $1
       for (div = 2; ; div++) {
         if (num % div == 0) {
           printf "Smallest divisor of %d is %d\n", num, div
           break
         }
         if (div*div > num) {
           printf "%d is prime\n", num
           break
         }
       }
     }

The break statement has no meaning when used outside the body of a loop. However, although it was never documented, historical implementations of awk treated the break statement outside of a loop as if it were a next statement (see Next Statement). Recent versions of Unix awk no longer allow this usage. gawk supports this use of break only if --traditional has been specified on the command line (see Options). Otherwise, it is treated as an error, since the POSIX standard specifies that break should only be used inside the body of a loop. (d.c.)